The shootings outraged Iraqis and raised questions about the US use of private contractors as security personnel during the Iraq War.

The US Court of Appeals for the DC Circuit ruled that the trial court “abused its discretion” in not allowing Nicholas Slatten, 33, of Sparta, Tenn., to be tried separately from his three co-defendants, even though he alone was charged with murder because he fired the first shots that sparked the bloodbath.

In a split ruling, the court also found the 30-year terms of the three others who had been convicted of manslaughter — Paul Slough, 37, of Keller, Tex.; Evan Liberty, 34, of Rochester, N.H. and Dustin Heard, 35, of Maryville, Tenn. — violated the constitutional prohibition against “cruel and unusual punishment,” the paper reported.

They got 30 years because they were also convicted of using military firearms while committing a felony, a charge that is usually used against gang members.

After Slatten fired, the others joined in, killing the civilians, which women and children at a traffic circle.

The guards claimed they were defending themselves after being shot at.